Kingdom: BacteriaPhylum: Proteobacteria

Class: Alpha Proteobacteria

Order: RickettsialesFamily: Rickettsiaceae

Genus: Rickettsia

(da Rocha-Lima, 1916)

SCIENTIFIC CLASSIFICATION

•Named after Howard Taylor Ricketts (1871–1910), who studied and eventually died of typhus

•Gram–Negative, Non-Sporeforming, highly pleiomorphic bacteria that can present as cocci

•Obligate intracellular parasites

•Depend on entry, growth, and replication within the cytoplasm of eukaryotic host cells (typically endothelial cells)

H. T. Ricketts (1871-1910)

TRANSMISSION

Rickettsia are generally carried by arthropods which include fleas, lites, mice, and ticks. Rickettsia can be transmitted most commonly via arthropod vectors but also by inhalation

and ingestion.

In most cases, the organism enters the human body through the skin cells into the blood vessels and induces phagocytosis.

Through the blood stream, the organism can travel to other vessels including the heart and brain.

Once in the blood, replication begins and lysis of the host cell occurs. Destruction, caused by lysis of the cell, results in leakage of blood and organ/tissue damage.

Infection of Endothelial Cells

Life Cycle

Symptoms

Different rickettsial infections tend to cause

similar symptoms

FeverHeadacheMalaiseA characteristic rash

As severe rickettsial diseases progress, people typically experience confusion and severe weakness.

CoughVomitingDifficulty breathingDiarrhea

In some people, the liver or spleen enlarges, the kidneys fail, and blood pressure falls dangerously low.

Death can result!

Tetracycline or Chloramphenicol

Treatment

No vaccines are currently available

Prevention

Do you know that…

• Despite the similar name, Rickettsia bacteria do not cause rickets.

• They have also been associated with a range of plant diseases. Like viruses, they only grow inside living cells.

• The majority of Rickettsia bacteria are susceptible to antibiotics of the tetracycline group

• Because the rash often does not appear for several days, early rickettsial infection is often mistaken for a common viral infection, such as influenza.

Prepared by : Jade Kenneth G. Lomansoc